1. Field of the Invention
The present invention relates to a screw, in particular a screw for use in nonmetal objects.
2. Description of the Related Art
Referring to FIG. 1, a conventional screw 1 comprises a screw head 10, a shank 11 extending from the head 10, a drilling portion 12 disposed at the distal end of the shank 11, and a plurality of threads 13 disposed on the shank 11; wherein a plurality of slots 14 are disposed on the surface of the shank 11, which results of the slight concavities in cross section PP P of FIG. 1 separately presented around the periphery of the shank 11, as shown in FIG. 2. In operation, the screw 1 is rotated into the wood object 2 by exerting the slots 14 to cut the fibers and accommodate the debris.
Generally, in regard to the resilience of the wood fibers and the expeditious rotation, the fibers would not be thoroughly received into the slots 14 with smaller spaces, thus rendering part of fibers to be severed into debris and the remaining part to be unsevered. Furthermore, due to the configuration of the slots 14, the debris is hardly guided out of the object 2 and is continuously accumulated therein; simultaneously, the unsevered and unbroken fibers are twisted round the shank 11. In this manner, the aforementioned debris and the fibers facilely make a larger screwing resistance and further cause the burden of the operators and the destruction of the object 2 while rotating the screw 1, thus affecting the screwing efficiency.